main() {
  var a = '123';
  //a = 123; //error
  print(a);
  String b = 'it is string';
  //b = 1; //error
  print(b);
  dynamic c = '123';
  c = 123;
  print(c);

  var lineCount;
  print(lineCount); //null,注意不是undefined!
}
//EOP
